The prefix 'il' is another variant of the term 'in' and the term conveys the idea of 'not'. The word was used during ancient times in the country of Italy and the period was approximately 700 B.C. But these days the variant of the term is used mainly and it is always used as a prefix and you can hardly find its use as an independent word. You can find the use of the word in several words and it is considered as one of the most widely used prefix. You can find its use in illegible, illegitimate, illicit, illegal and many other words.
If you take the use of the word in the word illegal it conveys the idea of something that is not legal and so the word legal is prefixed by the term 'il' to convey the phenomenon of negativity.
If you take the use of the word in the word illegal it conveys the idea of something that is not legal and so the word legal is prefixed by the term 'il' to convey the phenomenon of negativity.